(1) Field of the Invention
The present invention relates to a composition having a damping property and a damping member formed from this composition. More particularly, the present invention relates to a composition having a damping property, which comprises a petroleum resin and, incorporated therein, specific amounts of asphalt and mica, and a damping member for absorbing the vibrational energy of a building, a vehicle or the like, which is formed by molding this composition and is excellent in the adhesion follow-up property to convexities and concavities on a substrate.
(2) Description of the Related Art
It has been known that an asphalt composition is used for the production of a damping member for damping various vibrations and shocks, especially the vibrational energy in a building or vehicle.
By "damping", it is meant that a dynamic energy at deformation of a body is reduced by converting it to a thermal energy, and it is known that the damping member exerts functions of (1) reducing the amplitude at the time of resonance to reduce the emission of a sound and the stress, (2) reducing the propagation of a sound in a solid and the propagation of a vibrational energy and (3) damping a free vibration to reduce a shock sound.
As the damping method most widely adopted for attaining a damping effect in a vibration-generating structural element such as a building or vehicle, there can be mentioned a method in which a polymeric viscoelastic material such as asphalt is coated on the surface of a construction material. Examples of this method are disclosed in Japanese Patent Publication Nos. 52-50522 and 56-5469. Each of the inventions disclosed in these patent publications is characterized in that a specific additive is incorporated in asphalt used as the damping material to increase the damping loss coefficient of the asphalt.
Furthermore, Japanese Unexamined Patent Publication No. 57-29702 discloses a damping water-proof coating material comprising asphalt as the main component and mica having an aspect ratio of at least 90, which is dispersed in the asphalt so that the mica is oriented in the form of multiple layers, and Japanese Unexamined Patent Publication No. 58-28034 discloses a damping member prepared by scattering particles comprising a binder composed of asphalt and/or a thermoplastic synthetic resin as the main component and a rubber component and/or a wax as the modifier component, and at least one filler selected from the group consisting of fibrous fillers, powdery fillers and scaly fillers on a substrate and forming a sheet-like damping layer by a thermal or physical operation. Furthermore, Japanese Unexamined Patent Publication No. 52-39723 discloses a damping material comprising 60 to 80 parts by weight of asphalt, 3 to 9 parts by weight of a petroleum resin and 5 to 15 parts by weight of an organic staple fiber.
However, these conventional damping materials are defective in that since the asphalt content is high, the damping performance is not sufficient, the adjustment of the damping performance peak temperature is difficult, an inherent smell of asphalt is generated by heating at the kneading and applying steps and the handling is difficult and troublesome.